Barringer crater in Arizona is one of the few obvious meteorite sites on Earth. When mining geologist Daniel Barringer [1860-1929] began to investigate it, impact theories were unfashionable. Late 19th century geologists assumed volcanoes caused all craters on the Moon and Earth. In 1905 Barringer published that the Arizona crater was caused by a meteorite. The Barringer crater was formed about 50,000 years ago when 300000 tons of iron and nickel struck.